An electric power converting apparatus to be installed on a railway electric car includes a converter circuit and an inverter circuit that convert an electric power by causing a switching element configured with an IGBT (Insulated Gate Bipolar Transistor), an IPM (Intelligent Power Module), or the like to perform a switching operation.
The switching elements used in these electric power converting circuits have a conduction loss caused by electric current flows as well as a switching loss caused by the switching operation. Thus, to ensure that the switching elements operate in a stable manner, the heat caused by the loss needs to be efficiently dissipated into the air so that the temperature of the switching elements can be kept lower than a predetermined level.
In a common configuration of a conventional electric power converting apparatus for a railway electric car, the switching elements are positioned on a cooling device, and the cooling device is cooled by a forced air cooling using a fan, so that the heat generated by the switching elements can be dissipated. However, when such a forced air cooling method is used, it is necessary to install a cooling fan and a controlling device, resulting in a problem that the apparatus becomes bulky.
Meanwhile, for the purpose of downsizing the apparatus, a method has been proposed by which switching elements are cooled by using airflows caused by traveling of the railway electric car (see, for example, Patent Document 1 described below). The method disclosed in Patent Document 1 has advantageous characteristics where the structure is relatively simple, the maintenance cost is low, and the load to the environment is reduced because, for example, there is no noise caused by a cooling fan.    Patent Document 1: Japanese Patent Application Laid-open No. 2000-92819